A laser scanner that scans laser light toward a target object is known (for example, see Patent Literature (PTL) 1). Such a laser scanner includes a scanning mirror on the path of the laser light emitted from a light source. The scanning mirror scans the laser light emitted from the light source, toward the target object by oscillating about a predetermined axis at a resonant frequency. The resonant frequency is a frequency specific to the scanning mirror. As FIG. 6 illustrates, the gain characteristics of the scanning mirror are maximum at the resonant frequency. Accordingly, while the scanning mirror is oscillating at the resonant frequency, the amplitude of oscillation of the scanning mirror is maximum. The laser light reflected from the target object is reflected off the scanning mirror again, and then received by a photodetector. The distance between the laser scanner and the target object can be measured based on the laser light received by the photodetector in the above manner.
The laser scanner is also capable of measuring the shape of the target object based on the laser light received by the photodetector. The shape of the target object can be measured through arithmetic processing, by measuring approximately how much the reflected position (measurement point) of the laser light on the target object has temporally changed while oscillating the scanning mirror at a predetermined amplitude. Accordingly, it is important for the laser scanner to detect the laser light reflected from the same measurement point on the target object, at accurate timing.